Product Description:

The RD51.1-5N-055-L-NN-FW is a variable-speed drive controller from Bosch Rexroth Indramat within the RD 500 Drive Controllers series. Intended for plant automation, the unit converts fixed mains power into a regulated three-phase output for standard induction motors operating at commanded speeds. By varying output frequency and voltage, it lets the connected motor match process demand instead of running continuously at line frequency. It mounts inside a control cabinet, interfaces with higher-level PLCs, and supports adaptable motor control for conveyors, mixers, and pump stations where precise speed adjustment improves process consistency and energy efficiency.

Rated output reaches 55 kW, indicating the motor power available under nominal electrical conditions. The input stage uses a three-phase AC converter topology, and the permissible DC link is centered on 500 V, so associated components must be rated for that level. Closed-loop regulation is not provided; instead, the drive uses U/f curve control, in which output voltage rises with frequency to maintain motor flux in the connected induction motor. This operating method suits general-purpose speed control tasks where simple motor regulation is preferred over feedback-based control. Thermal management relies on forced-air cooling, so adequate ducting and clearance are required to keep the heat sink within its temperature class.

The drive is a first-generation design, denoted by 1, and its hardware layout matches the earliest RD 500 mechanical footprint. It is supplied without a built-in brake chopper, so applications that require rapid stopping need an external resistor module to absorb regenerated energy during deceleration. The control terminals are not equipped with optional technology add-ons and therefore support only the standard drive functions provided by the base unit. In addition, firmware must be ordered separately, and the correct software release must be installed before the unit is energized.